This invention relates to a controller for a textile machine. It relates more particularly to a controller capable of generating instructions for most conventional circular knitting machines to cause the machines to knit fabrics in accordance with preselected patterns.
The knitting machines with which we are concerned here are equipped with individually operable needles or other appropriate knitting instruments and means for exercising selective and individual control over these instruments according to predetermined patterning requirements. Since the general construction and operation of the knitting machines to which the present invention is applicable are well-known and familiar to those conversant with the knitting art and as the invention is entirely concerned with an improved means of needle selection, we shall not describe the knitting machine per se except as necessary to clarify the operation of the subject controller.
Suffice it to say at this point that the machine includes yarn feeders with electromagnetic needle selectors which are energized or not in a predetermined manner to knit the preselected patterned fabric. Such knitting machines are described in some detail in U.S. Pat. Nos. 1,927,016; 3,313,128; 3,449,928. Both the fabric and a set of knitting needles are rotated past a circular array of yarn feeders. A needle selector at each feeder is controlled in synchronism with fabric movement to produce given stitch colors or types at given locations on the fabric in accordance with the desired pattern.
In the electronic knitting machines with which we are primarily concerned here, the selectors at the feeders are solenoid-operated and electronically controlled by means of a controller. Controllers as such are not new, an example of one being disclosed in British Patent No. 1,278,304. They are programmed from a tape or film and simply execute instructions for actuating the selectors at the appropriate times to generate the desired fabric patterns. The instructions are retrieved from a punched tape or other such recording medium.
Conventional controllers, however, are not entirely satisfactory for controlling the large, high-speed knitting machines which are coming into widespread use at the present time. In the first place, their capacity is limited, which places corresponding constraints on the size and complexity of the basic patterns which they can instruct the machine to knit. Also, in many cases, the instructions which they are able to deliver permit the associated knitting machine to knit only a square basic pattern, i.e. a pattern composed of an equal number of columns and rows of stitches.
Conventional controllers are disadvantaged also in that, once set up to deliver instructions for knitting a certain basic pattern, they cannot easily be adjusted to instruct an associated knitting machine to knit a different pattern or a variation of the original pattern; they must obtain instructions from a different tape. Moreover, with conventional controllers, it is relatively difficult to change the colors in the basic pattern; either new detailed instuctions must be entered on the control tape, or multiple tapes used, or the colors of the yarns at the various knitting machine feeders have to be changed. In each case, the system must be shut down for a relatively long time, resulting in a drop in productivity.